Ahead of today's sole practice session, the air temperature is 27 degrees C, while the track temperature is 40 degrees.

Already destined to start from the back of the grid tomorrow after taking on a new power unit, Valtteri Bottas has taken another new unit overnight after a leak was discovered.

It's unclear if this was the result of the clash with Romain Grosjean, whose Friday work ended up "in the bin" due to the shortage of spares as Haas continues its 'pick 'n' mix' approach to its chassis and aero components.

Despite his issues, Bottas topped the timesheets in both sessions yesterday, a day when both sessions witnessed red flag stoppages due to technical issues (Ricciardo) and close encounters with the barriers (Vettel).

Lewis Hamilton was unhappy with the lack of pace of his Mercedes, among other things, while Ferrari, once again, appeared to be losing out to both the German team and Red Bull.

The 'best of the rest' battle remains as competitive as ever, with no clear picture yet emerging. That said, the battle for fifth in the team standings should provide some fun with Toro Rosso needing just 8 points to overhaul Renault.

The lights go green and Raikkonen is first out, followed by the Haas pair, Grosjean, in particular, facing a very, very busy sixty minutes.

There's a fair mixture of hards, mediums and softs as more drivers emerge.

"The steering is slightly bent to the left," reports Gasly.

In many ways, the first part of this session, much like all of FP1, is unrepresentative of the rest of the weekend, therefore most drivers prefer to wait as the sun begins to lower in the sky and along with it the temperatures.

Fourteen minutes into the session Norris posts the first time of the day (38.987), which is the cue for the Renaults to appear. Hulkenberg is told to push a little harder on his out lap.

As more times are posted, Bottas is the first of the big guns to head out and unsurprisingly heads straight to the top of the sheets with a 37.911, despite a very scrappy lap. Following his clash with Grosjean yesterday, the Finn admitted that he is focussing all his efforts on the race and the need to make a whole load of overtakes.

Vettel, like Bottas on softs, subsequently goes second (38.170), while Leclerc can only manage eighth (40.300).

A 37.699 sees Hamilton go top by 0.212s, while Ricciardo goes fourth with a 38.271, ahead of Albon (38.816). The Thai driver is the only front-runner on mediums.

On softs, Verstappen shoots straight to the top with a 37.202, eclipsing Hamilton by a mighty 0.497.

Magnussen goes ninth with a 38.884, with teammate Grosjean going sixth (38.726) moments later.

"I've got a fair bit of vibration on the straight," reports the Frenchman. "Nothing stopping me going, but..."

After 28 minutes Kubica is the only driver yet to post a time.

"I don't think my dash is working, it just says 999," says Verstappen. To compound his frustration, Hamilton posts 36.640 and Bottas 37.189.

Replay shows a big wobble in the final corner for Hamilton, a corner that caught out a number of drivers yesterday.

As Sainz is told to stop for a "nose job change", Stroll reports that his dash is telling him he is in "limp mode", which is what Hamilton had in FP1.

Both Ferraris head out on mediums, the Italian team no doubt considering qualifying on the yellow-banded rubber this afternoon.

Vettel immediately goes quickest in S1, but Leclerc subsequently goes quicker. In S2 the Monegasque continues to have the edge. At the line Vettel posts 36.975 to go second, with his teammate posting 37.010 moments later, having lost ground in S3.

The Mercedes pair head out on softs, as Leclerc goes quicker in S1 on his next flying lap only to discover that his tyres are only good enough for the one hot lap.

Vettel is told that at Turn 21 he can brake seven metres later.

A massive lock-up for Hulkenberg leaves the German with an equally massive flat-spot. As a result he remains 12th (38.884).

Verstappen and Sainz are both on track, both sporting softs.

The Dutchman third (36.729) and the Spaniard to seventh (37.691).

Ricciardo consolidates sixth with a 37.615. "I'm pretty happy with that," he says, "with the tyres... I probably can't get more out of it."

Fourth and fifth, the Ferrari pair are the only drivers to have used the mediums for their qualifying sims.

A 36.927 sees Albon go fourth, 0.2s off his teammate's pace.

Perez improves to seventh and Stroll thirteenth. As the Mexican reports coming out of his exhaust, Raikkonen gets a face full of it as if to prove the point. The Finn is currently 19th.

A 36.566 sees Verstappen go quickest, just 0.074s ahead of Hamilton.

Vettel heads out on fresh softs with just two minutes remaining. Leclerc heads out on fresh mediums. However, both appear to be merely scrubbing the tyres, and not attempting a late flyer.

"That was really cool from Vettel," says Grosjean, "he gave me a nice slipstream, but the last sector was no good."

The session ends. Verstappen is quickest, ahead of Hamilton, Bottas, Albon, Vettel, Leclerc, Perez, Ricciardo, Sainz and Gasly.

Grosjean is eleventh, ahead of Kvyat, Norris, Magnussen, Stroll, Raikkonen, Hulkenberg, Giovinazzi, Russell and Kubica.

Check out our Saturday gallery from Yas Marina, here.